1. Field of Invention
The present invention relates to a lens control method and a control system thereof, in particular, to a control method of auto-retracting a lens of an image capture apparatus and a control system using the same.
2. Related Art
An image capture apparatus (e.g., a digital camera) is a novel product combined with optical, fine mechanical, and electronic technologies, which converts an image captured by a lens of a camera into a digital image signal by a charge coupled device (CCD) and stores the digital image signal into a storage medium, such as a magnetic disk, optical disk, or IC memory card, through being processed by electronic circuits. Furthermore, the image may also be displayed on all kinds of displays (e.g., a television or monitor) immediately, for performing various reuse functions of images, e.g., editing or modifying, so that it is fairly convenient and saves time and money.
As the digital camera has become a mainstream consumer electronic product in recent years, consumers have increasingly high requirements on the functions of the digital camera such as a high pixel, short film shooting function, large LCD display screen, large memory capacity, small volume, and small weight. In this case, it has become an important challenge for engineers in designing digital cameras to prolong the use and standby time of a battery.
Since there are various enterprises and brands of batteries used by the digital cameras, it requires to conduct a great deal of tests and complex estimations to predict whether the battery is out of power. However, the batteries have great variations and chemical formula of the batteries also changes rapidly, resulting in increasingly high complexity and high failure rate when predicting the residual power of the battery. As a result, it is a difficult task for estimating the residual power of the battery of the digital camera correctly. In a user's using experiences, the digital camera is often abnormally powered off when the battery runs out of power, and what's worse, the lens still remains un-retracted. In this case, it is rather inconvenient for the user to carry along the camera with the lens un-retracted, and the lens may even possibly suffer from damages due to being crashed.
Currently, in order to solve the above un-retracted problem of the lens resulted from running out of power, some power supply management designs involve raising a threshold value for the point of running out of power. In this way, the digital camera is ensured to be able to retract the lens with the residual power before the digital camera reaches the point of running out of power. Unfortunately, such power supply management designs further reduce the original available power capacity, thus sacrificing a number of available shots of the digital camera. Additionally, the relevant prior art concerning a power-saving mechanism of the digital camera can be obtained with reference to ROC Patent Publication No. I299813, which discloses a power-saving method of an image capture apparatus. The power-saving method omits the power consumption resulted from a standby mode and repeatedly retracting and un-retracting the lens, thus raising the number of shots of the image capture apparatus. However, a system which includes a control algorism and corresponding hardwares for auto-retracting the lens in the case of abnormal power failure is not disclosed.
Accordingly, how to provide a new technology for auto-retracting the lens in the case of abnormal power failure becomes one of the problems to be urgently solved by the research personnel.